1. Field of the Invention
The present invention relates to an interlocking gear control mechanism used in a magnetic tape recording/playing apparatus, and more particularly to a gear control mechanism suitable for use in a magnetic tape recording/playing apparatus to utilize the drive force of a motor in order to effect such mechanism operations as loading of a magnetic tape pack.
2. Description of the Prior Art
In the conventional magnetic tape recording/playing apparatuses, it is practically rare that loading of a magnetic tape pack, forward movement of head plate, etc. are effected as driven by the motor; in some of the conventional magnetic tape recording/playing apparatuses, after the tape pack is taken to the innermost position within the apparatus, it is carried over a remaining short stroke into the recording/playing position by an intermittent action of the portion of a tape pack loading gear which is provided with no teeth. This conventional system is advantageous in that the tape pack can be disengaged from the gear when engagement is unnecessary. However, since the tape pack loading mechanism is operated with a cam disposed coaxially with the rotating intermittent gear, the operating stroke cannot be so large; in particular, in case the loading of tape pack needs a large stroke, the tape pack setting mechanism has to have a very large volume. Further, a system in which a rack plate and gear are used for this purpose of tape pack loading has been proposed; in this case, however, in order to start the loading operation and stop the operation after the tape pack is set in place, (1) a motor for exclusive use for the operation is provided which is energized or deenergized to start or stop the operation, or (2) the attractive force of an electromagnetic plunger is utilized to let the rack plate engage with the gear, thus starting the loading operation, and the electromagnetic plunger is deenergized so as to lose its attractive force, thus disengaging the rack plate from the gear to stop the loading operation, or (3) a clutch mechanism is provided between the motor drive and the rack drive gear so that the rack plate having moved a necessary stroke is made to slip by the clutch mechanism. However, in the case where the motor for special use for the loading operation is employed, no disengagement is made between the rack plate and gear. Consequently, when the rack plate is returned for resetting the tape pack, the motor is a kind of load so that the rack plate is not smoothly moved. Further, the provision of an exclusive-use motor results in a larger loading mechanism and thus higher manufacturing costs. In the case where the electromagnetic plunger is employed, the loading mechahism is of a large volume and the costs of manufacture are consequently expensive, as in the case of the exclusive-use motor being provided. In the case that the clutch mechanism is adopted, the mechanism itself causes the loading operation to be unstable, and since the clutch mechanism always makes the rack plate slip, which causes an extra load to the drive motor and the durability of the motor and the other to be degraded. In addition, adverse affects such as wow are caused to take place to the mechanical properties. The clutch mechanism is apt to act as load to the operation of returning the rack plate when the tape pack is reset.